Are You on a Starvation Diet?


Most dieters have heard about reducing their calories too low and entering into a “Starvation Diet”. Some refer to the starvation diet as a level of calories where you are no longer able to nutrients that your body needs without supplements.

Another interpretation is that you are eating so few calories, that you’re body just holds onto everything because it thinks it’s starving. This is the “starvation diet” that I wanted to look into.
If you were to eat 800 calories a day for the rest of your life, and you body burned 1000-2000 calories a day just to lay in bed, at some point you would weigh 0 lbs…

But that doesn’t happen. Your body has mechanisms in place to ensure that you live. Kinda nice of it, don’t you think?

When people have been on a low calorie diet for an extended period of time, sometimes they state that they have metabolic damage or their metabolism is broken. Well, that's not quite true and here's why....

The Energy Balance Equation

To start, we have to talk about how weight loss and weight gain occur. The process is called the Energy Balance Equation and it goes like this:

-To lose weight, you eat less than you expend.
-To gain weight, you eat more than you expend.

Simple…. But not really.

The energy balance equation does not tell us anything except that bodyweight should be lower or higher. It does not tell us that your bodyfat will change, just the number on the scale will change. The Energy Balance Equation doesn’t take into account things like hormones, macronutrient intake, exercise type, age, genetics, etc. So if the calorie counter says your burning 2000 calories a day and you’re only eating 1500, you should lose weight, right? Sometimes this works, sometimes it doesn’t.

It’s because this equation is a lot more complicated than it sounds.

Energy In

Energy in is everything that you eat. Whether you eat more than your body needs or less, it is still considered energy in. Food energy is typically measured in kilocalories (kcal) but most people shorten it even further and refer to it as calories or cals.
  • Calories on the label don’t match what is in the meal exactly. Manufacturers are allowed up to a 25% discrepancy on the label of the food. When they calculate the calories in the food for their label, they’re not checking every package and they’re using outdated methods.
  • For now, let’s assume that if the calories on the label were right, our body doesn’t absorb, store or use everything that we put in it. Due to absorption, you could have a difference of up to 25% of calories absorbed (either less or more).
We absorb more calories from processed and cooked foods, because they’re easier to digest. Therefore, if processed foods are easier to digest, and whole foods require more effort, then the more processed foods that you eat, the more of the calories from that food you are likely to absorb and probably over eat because they taste So. Damn. Good. Also, you burn less calories digesting more processed foods.

Absorption

The bacteria in our gut are different, so two people can eat the exact same things and absorb different amounts of them. For example, USDA researchers had test subjects to consume 42 grams of walnuts daily for three weeks. The calories were adjusted to match the control period. They found that people absorbed 146 of the 185 predicted calories for a 28g serving and 219 of the 278 calories for the 42g serving. That’s only 79% of the calories that are being absorbed.

In addition, they found that fecal fat content was higher, meaning people are excreting more of the fat than they are absorbing it. Due to the energy availability from nuts being less than predicted, this may be why consumption of nuts leads to beneficial effects on bodyweight and BMI.

Calorie Estimates

Calorie estimates from calculators are just that.. estimates. Unless you live in a lab you cannot know exactly how many calories your body burns everyday. These calorie calculator estimates can be off by up to 20% in either direction from what you and your own body needs.

Calories tracked by humans are unreliable. Now I’m not saying that you’re lying and intentionally sabotaging yourself. It’s just that humans are known to perceive things differently. What you may see as being 2 Tablespoons of oil may actually be 5-7 Tablespoons if you measure it out. You may not always correctly calculate the bites that you take of someone else’s food… either you forgot when you track you meal or it’s hard to accurately track because it’s such a small amount that you don’t track it.

But your body does. Your body tracks EVERYTHING.

Total Daily Energy Expenditure (TDEE) or Energy Out

Energy out is a lot more complicated than move more. Factors that influence the Energy Out part of the equation:
  1. Basal Metabolic Rate (BMR)- what your body burns daily to function (breathing, thinking, etc)
  2. Thermic Effect of Food (TEF)- how many calories your body burns to digest certain foods.
  3. Exercise Activity Thermogenesis (EAT)- calories burned through purposeful exercise
  4. Non-exercise activity thermogenesis (NEAT)- what your body burns doing non-exercise movements like fidgeting and keeping good posture.
Each of these variables in the equation are variable within themselves. The only way to get a 100% accurate reading is to live in a lab and take measurements every minute. And again the calorie measurements from your fitness tracker, calorie tracker website, or machine may not be accurate. You may be overestimating what you are burning.

What Happens When You Diet

When you diet, you typically reduce calories and add in/ increase exercise. What this means to your body is: Calories in have lowered so I must lower calories out to match.
To match, your body:
  • slows digestion (more calories absorbed)
  • lower RMR (due to lower body weight)
  • lower thermic effect of food (you’re eating less, so there’s less to digest)
  • Burns less calories exercising (due to lower body weight)
  • Lower NEAT calories burned (you’re fidgeting less as your body is trying conserve energy)
Even though you are eating fewer calories and exercising, your body is fighting you and compensating by reducing your TDEE and burning fewer calories. This has been called adaptive thermogenesis and can result in a drastic (more than expected) drop in TDEE to attempt to restore your body’s baseline weight. Effects of adaptive thermogenesis have been found to persist in subjects who are no longer actively losing weight and have maintained their weight loss for over a year.

Hormone Reactions

Hormones are affected by lower calorie intake and may trigger things like cravings, hunger signals, and water retention. Leptin is hormone that is secreted by your fat cells and indicates the size of your fat stores to the brain. When calories in are lowered and your body has to rely on fat stores for energy, leptin is reduced in the blood stream. This signals to your brain says that fat storage is being depleted and we need to re-stock.

Similar to leptin, insulin is also related to fat storage and give your brain the “I’m full” signal. This effect explains why carb heavy meals make you feel full in the moment, but doesn’t always last. Kind of like Chinese food…. Alternately, ghrelin has been shown to increase with fasting and decreasing after eating. Ghrelin stimulates appetite.

Enter cravings and hunger pains.

Another hormone, which I’m sure most people have heard of, Cortisol, also plays a role in weight loss. Cortisol is released when your body feels stress. This can be mental stress (freaking out about deadlines, anxiety over your new diet) or physical stress (rough workout, lowering calories). When cortisol levels are increased you can retain water, making it seem like progress is nil.

Actionable Ways to Lose Weight

  • Minimize the size of the caloric deficit. Set your calories as high as possible while still losing weight slowly.
I realize that seeing the scale drop quickly at first gives you hope and shows that your efforts are being rewarded, but reducing your calories right off the bat leaves no wiggle room in the end. In addition, it has been shown that the larger the deficit in calories, the greater loss of muscle mass. This may sound ok, because not everyone wants to be super muscular, but in order to be “toned” you need something to “tone” against (hint: it’s muscle). So instead of jumping on the 500 calorie deficit bandwagon, try for something more moderate, like 200-300 calories.

Related post: How to Calculate Your Calories and Macros
  • Readjust your calories when weight loss plateaus. When the current calories you are eating no longer are producing weight loss, you should readjust your calories.
If you are still losing weight, you do not need to adjust your calories. Just because some people adjust their calories weekly, biweekly, or monthly, doesn’t mean that you have to.  Only adjust your calories when weight loss has stalled.
  • Reduce cortisol levels by reducing stress.
If your diet is stressing you out and causing you anxiety about what you need to eat, when you need to eat, what you can eat and what you can’t eat.. maybe it’s not the right diet for you… find a diet that does not cause you any further stress.
  • To maintain your new weight, you need to eat for your new weight.
Do not assume that once you have lost the weight that you can go back to eating the way you did before. Something I hear about all too frequently with yo-yo dieting is that they gained all the weight back when they stopped eating [fill in the blank}.

References

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Baer DJ, Gebauer SK, Novotny JA Measured energy value of pistachios in the human diet. Br J Nutr  2012;107(1):120–5.
David J Baer, Sarah K Gebauer, Janet A Novotny, Walnuts Consumed by Healthy Adults Provide Less Available Energy than Predicted by the Atwater Factors, The Journal of Nutrition, Volume 146, Issue 1, January 2016, Pages 9–13, https://doi.org/10.3945/jn.115.217372
Ariyasu H, Takaya K, Tagami T, Ogawa Y, Hosoda K, Akamizu T, Suda M, Koh T, Natsui K, Toyooka S, Shirakami G, Usui T, Shimatsu A, Doi K, Hosoda H, Kojima M, Kangawa K, Nakao K: Stomach is a major source of circulating ghrelin, and feeding state determines plasma ghrelin-like immunoreactivity levels in
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Doucet E, St-Pierre S, Almeras N, Despres JP, Bouchard C, Tremblay A: Evidence for the existence of adaptive thermogenesis duringweight loss. Br J Nutr 2001, 85:715–723.
Rosenbaum M, Hirsch J, Gallagher DA, Leibel RL: Long-term persistence ofadaptive thermogenesis in subjects who have maintained a reduced body weight. Am J Clin Nutr 2008, 88:906–912.
Rosenbaum M, Leibel RL: Adaptive thermogenesis in humans. Int J Obes, 2010, 34(Suppl 1):S47–S55.
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